The traditional method for the collection of small quantities of fluids, gases or other biomolecules from a patient utilizes mechanical perforation of the skin with a sharp device such as a metal lancet or needle. Additionally, the typical method of administering anesthetics or other pharmaceuticals is through the use of a needle.
These procedures have many drawbacks, including the possible infection of health care workers and the public by the sharp device used to perforate the skin, as well as the cost of handling and disposal of biologically hazardous waste.
When skin is perforated with a sharp device such as a metal lancet or needle, biological waste is created in the form of the "sharp" contaminated by the patient's blood and/or tissue. If the patient is infected with blood-born agents, such as human immunodeficiency virus (HIV), hepatitis virus, or the etiological agent of any other diseases, the contaminated sharp poses a serious threat to others that might come in contact with it. For example, many medical workers have contracted HIV as a result of accidental contact with a contaminated sharp.
Post-use disposal of contaminated sharps imposes both logistical and financial burdens on the end user. These costs are imposed as a result of the social consequences of improper disposal. For example, in the 1980's improperly disposed biological wastes washed up on public beaches on numerous occasions. Improper disposal also permits others, such as intravenous drug users, to obtain contaminated needles and spread disease.
There exists an additional drawback of the traditional method of using a needle for administering anesthetics or pharmaceuticals, as well as for drawing fluids, gases or other biomolecules. The pain associated with being stabbed by a the sharp instrument can be a traumatizing procedure, especially in pediatric patients, causing significant stress and anxiety in the patient. Moreover, for drawing fluids, gases or other biomolecules the stabbing procedure often must be repeated before sufficient fluid is obtained.
The current technology for applying local anesthetic without the use of needles typically involves either (a) topical lidocaine mixtures, (b) iontophoresis, (c) carriers or vehicles which are compounds that modify the chemical properties of either the stratum corneum, or the pharmaceutical, and (d) sonophoresis which involves modifying the barrier function of stratum corneum by ultrasound. A cream containing lidocaine is commonly used, especially in pediatric patients, but needs to be applied for up to 60 minutes, and anesthesia is produced to a depth of only about 4 mm. The lack of lidocaine penetration is a consequence of the barrier function of the stratum corneum. Inherent problems with iontophoresis include the complexity of the delivery system, cost, and unknown toxicology of prolonged exposure to electrical current. Additionally, the use of carriers or vehicles involves additional compounds which might modify the pharmacokinetics of the pharmaceutical of interest or are irritating.
Thus, a need exists for a technique to remove fluids, gases or other biomolecules or to administer anesthetics or other pharmaceuticals which does not require a sharp instrument. The method and apparatus disclosed herein fulfill this need and obviate the need for the disposal of contaminated instruments, thereby reducing the risk of infection.
Lasers have been used in recent years as a very efficient precise tool in a variety of surgical procedures. Among potentially new sources of laser radiation, the rare-earth elements are of major interest for medicine. One of the most promising of these is a YAG (yttrium, aluminum, garnet) crystal doped with erbium (Er) ions. With the use of this crystal, it is possible to build an erbium-YAG (Er:YAG) laser which can be configured to emit electromagnetic energy at a wavelength (2.94 microns) which is strongly absorbed by, among other things, water. When tissue, which consists mostly of water, is irradiated with radiation at or near this wavelength, energy is transferred to the tissue. If the intensity of the radiation is sufficient, rapid heating can result followed by vaporization of tissue. In addition, deposition of this energy can result in photomechanical disruption of tissue. Some medical uses of Er:YAG lasers have been described in the health-care disciplines of dentistry, gynecology and ophthalmology. See, e.g., Bogdasarov, B. V., et al., "The Effect of Er:YAG Laser Radiation on Solid and Soft Tissues," Preprint 266, Institute of General Physics, Moscow, 1987; Bol'shakov, E. N. et al., "Experimental Grounds for Er:YAG Laser Application to Dentistry," SPIE 1353:160-169, Lasers and Medicine (1989) (these and all other references cited herein are expressly incorporated by reference as if fully set forth in their entirety herein).